Production of glycol monoethers



United aw o 2,91 ,520 PRODUCTION OF GLYCOL MONOETHERS Henri Normant, Paris, France, assignor 'to'Societe des Usines vChimiques Rhone-Poulenc, Paris, France, a in orporation of France No Drawing. Application July 15, 1957 Serial No. 671,688

priority, application France July 19, 1956 Claims. (Cl. 260-611) This invention relates to the production of glycol mono-' ethers and more particularly to the production of mono- ;ethers of primary-tertiary and primary-secondary glycols of the general formula: R\ /OH 5 R ore-0.11% V in which R and R" are saturated or unsaturated aliphatic, isbcyclic or h y i ra i als 3. 57 13 i$ yd atom or a saturated or unsaturated aliphatic isocyclic or heterocyclic radical, or R and R form with the'carbon atom to which they are attached acyclic radical.

t i wn to Pre a e ,p i n m ti ry mo y e hers o thir r yp y reac ng cream-magn sium ompounds with ethyl ethoxy acetate, the reaction apparently taking the following course:

' R OH it CHg-OC2H5 This method-however is only applicable to ethers of glycol'siin which the .two radicals R and R are identical.

It has alsobeen proposed to condense organo-magnesium compounds with ethoxy ketones, the reaction proceeding as follows:

. in a medium of ethyl ether according to the reaction:

R" V (+H C +C1;O.H Bi] V However, it has only been possible in this method to use higher ketoneselg. those in the series methyl hexyl ketone toir1 ethyl decyl ketone, i.e. ketones in which R is a long-chain alkyl group andR' is a methyl group, with yields from'ldto 58%. With the lower ketones, such as acetone, theauthor indicates that the yields are even M CiO onion."

1 smaller and that he has 'not'been able to obtain pure glycol ethers. Moreover, the author indicates that the method has not been successful with aromatic ketones,

- Such as acetophenone and that though the method has been applied to aldehydes, it proved without" success.

It has now been found that the reaction of chlor'omethyl ,ethers'with ketones in the presence of magnesium may be carried'outto afford excellent yields if the medium of 2,916,520 Patented Dec. 195,9

ethyl ether is replaced by a cyclic ether such as tetrahydrofuran, tetrahydropyran and homologues thereof. Under .these working conditions the method is applicable generally to all the ketones of the RCOR type, in which R and R can be alkyl or aryl groups or form a fingilwith the CO. group. i

It has also been found that, using the same cyclic ethers, the condensation of chloromethyl ether can'also be carried out with aldehydes ,(R=H) with formation of the corresponding primary-secondary glycol ethers, ac cording to the reaction:

According to the present invention, therefore, there is Prov de a P P$ for t e duc n f yc ethers f the eral fo mu oramononuclear aryl, aralkyl or cycloalkyl radical and in the case of R a hydrogen atom or a saturated or unsaturated aliphatic, hydrocarbon radical, or a mononuclear aryl, aralkyl or cycloalkyl radical and taken together form withfthe carbon atom to which they are attached a cyclic nucleus, and R" is a saturated or unsaturated li h ti hydrocarbo -r a or a mononuc e a y 1 aralkyl or cycloallcyl radical, which comprises reacting a compound of'the general formula ROO R' with a chloromethyl ether of the formula CICH 'O R in the presence of magnesium in a medium of a cyclic ether, decomposing the magnesium compound formed and isolatiiig the' glycol ether thus produced. I

' the scope of the foregoing statement of theinvention the process is preferably applied to the production f mpPQQd i Wh R is an y ro p contai n p to I Z'c'arbon atoms or a'corresponding ethylenicallyune saturated group, or a saturated cycloalkyl radical with a five or six carbon ring, and R is a hydrogen atom or any of, the foregoing types of group, or wherein Rand R are jointly with the carbon atom to which they are attached a benzene ring or a corresponding more saturated ring, and R"-is any of the. groups referred to above, and these possibilities represent a preferred sub-group of compounds according to the invention.

The glycol ethers obtained by the present invention are very valuable organic intermediates because they can easily be transformed into aldehydes by the action of acids according to the reaction mechanism:

R on R R-CH OH=OHCH O are. Obtained because of a migration of the double bond.

in the chloromethyl ethers of the formula ClCH -O-R used as starting materials R" can be a methyl, ethyl or higher homologous group, or aryl. If the glycol ethers are to serve for the preparation of aldehydes, it is preferred to use chloromethyl methyl ethers and chloromethyl ethyl ethers. The chloromethyl ethers are very easy to prepare by the reaction of formaldehyde, hydrochloric acid and an alcohol.

Ketones used as starting materials are of the formula R-CO-R'. Suitable compounds are those in which:

(1) R is a methyl radical and R is a saturated. or unsaturated aliphatic radical. Examples are acetone, methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone and higher ketones and unsaturated ketones such as mesityl oxide and methyl heptenone.

(2) R is a methyl radical and R an aryl radical, a

saturated or unsaturated aryl-aliphatic radical or a saturated or unsaturated cycloaliphatic radical. Examples are acetophenone, benzyl acetone, benzylidene acetone, p-isopropylacetophenone and B-ionone.

(3) R is a radical other than methyl and R is an aliphatic or cyclic radical. Examples are diethyl ketone, ethyl propyl ketone, ethyl butyl ketone, diisobutyl ketone, benzophenone and phenyl cyclopropyl ketone.

(4) R and R form a ring with the C group. Examples are cyclohexanone and homologues thereof.

Aldehydes (R=H) used as starting materials may be saturated or unsaturated aliphatic, aromatic, or heterow cyclic aldehydes. Particularly suitable aliphatic aldehydes are the higher aldehydes comprising 5 to 12 cabon atoms, unsaturated aldehydes such as acrolein, crotonal and pentenal, aromatic aldehydes such as benzaldehyde and its homologues, hydroxy aldehydes such as veratraldehyde and piperonal, and heterocyclic aldehydes such as furfural.

The reaction is carried out by bringing the chloromethyl ether and the ketone or aldehyde into contact with magnesium, preferably activated by mercuric chloride, in the presence of a cyclic ether such as tetrahydrofuran, tetrahydropyran or a homologue thereof.

The transformation of the ethers obtained into aldehydes can be carried out by the conventional methods: treatment with sulphuric acid, p-toluene sulphonic acid, formic acid or oxalic acid.

The following examples will serve to illustrate the invention.

EXAMPLES 9.72 g. of magnesium are placed in a flask and covered with dry tetrahydrofuran. is added and the mixture stirred for 2 minutes.

From an ampoule containing 38 g. of freshly distilled chloromethyl ethyl other free from hydrochloric acid, diluted with 2 volumes of dry tetrahydrofuran, to 15 cc. are poured into the flask and stirred. As soon as the reaction has started, the flask is immersed in an ice bath. The remainder of the chloromethyl ether solution is then added dropwise and there is added, at the same titme, from another ampoule, 35 g. of amyl methyl ketone diluted with an equal volume of tetrahydrofuran, so that the additions are finished at the same time. The mixture is left to stand, and then decomposed, while still in the ice bath, by a cold saturated solution of ammonium chloride. The aqueous layer is then decanted and extracted with ether. The ethereal extract is added to the organic phase and the whole is dried over sodium sulphate. The solvents are driven oil and the residue distilled over reduced pressure (12 mm. of mercury). 48 g. of l-ethoxy-2-methyl-2 heptanol are obtained, boiling between 87 and 90 C.

The middle fraction, which boils at 87 C./11 mm. Hg, has the following constants: n =l.4281; d =0.866.

By treating the ethoxy methyl heptanol with formic acid, 2-methyl heptanal is obtained in a yield of 71%, this substance boiling at 51 C./11 mm. Hg.

The general process just described, applied to a series of aldehydes and ketones gives the results indicated in the 0.5 g. of mercuric chloride 4 following tables, which shows the yield of the relevant glycol ether and its boiling point at the pressure indicated.

Table I CONDENSA'IION WITH CHLOROMETHYL ETHYL ETHER R\ R\ /OH /OO CHzGl-O-GzHa /C\ R R CHiO 01H;

Glycol ether Initial materials Yield, B P., 0 Percent pressure,

mm. Hg

Acetone 70 128/764 Methyl ethyl ketone, 76 48/14 Methyl isobutyl ketoile 87 65/12 Methyl amyl ketone 93 87/11 Methyl isobutenyl ketone 50 66/10 Methyl heptenone 102/12 Ar etnnhennnp 55 109/11 Benzyl methyl ketone-.- 70 130/16 Benzylidene acetone 50 112-114/0. 5 Isopropyl acetophenone 70 104/0. 5 B-Ionone 76 111-112/0. 7 pj-Isopropyl benzyl methyl ketone 87 109-11110.

iisobutyl ketone 45 103/17 Cyelopropyl phenyl ketone 60 128-132/11 Benzophenone 72 126/0. 5 Cyplnhexannnn 76 88/1 Hepranal 68 103/11 Acr 30 51/13 46 64/10 70 85/15 88 -122/12 82 137-14010. Piperonal 80 /0. 4

Table II OONDENSATION WITH OHLOROMETHYL METHYL ETHER R\ 1K /0H 00 CHzCl-O-CH: --v /C\ R I R CHQO CH:

Glycol ether Initial materials Yield, B.P., 0.] Percent pressure,

mm. Hg

Methyl isobutyl ketnnn 52 48/12 Ethyl butyl 75 84/10 I claim:

1. A process for the production of a glycol ether of the general formula in which R and R are selected from the class which consists of hydrogen atoms, saturated and unsaturated aliphatic hydrocarbon radicals, mononuclear aryl, aralkyl and cycloalkyl radicals, and molecular fragments which with the adjacent carbon atom complete a cycloaliphatic ring, at most One of the two being hydrogen, and R" is selected from the class which consists of saturated and unsaturated aliphatic hydrocarbon radicals and mononu- I clear aryl, aralkyl and cycloalkyl radicals, which comprises reacting a compound of the general formula' R.CO.R' with a chloromethyl ether of the general formula CICH OR" in the presence .of magnesium in a medium of a cyclic ether selected from the group which consists of tetrahydrofuran, and tetrahydropyran, hydroi 3. A process according to claim 1, which comprises carrying out the reaction in the presence of magnesium activated by mercuric chloride.

4. A process according to claim 1, which comprises carrying out the reaction in a medium of tetrahydrofuran.

5. A process according to claim 4, which comprises carrying out the reaction in the presence of magnesium activated with mercuric chloride.

References Cited in the file of this patent UNITED STATES PATENTS 2,422,956 Elderfield et a1 June 24, 1947 6 FOREIGN PATENTS Germany Ian. 16, 1907 OTHER REFERENCES 5 Sommelet.: Annales de Chimie et de Physique, 8

Ser., vol. 9, pp. 531-536 (1906).

Cherbuliez et a1.: Helvetica Chimica Acta, vol. 26, pp. 2251-2252 (1943).

Elderfield et a1.: J. Am. Chem. Soc., vol. 72, pp. 10 1334-1345, March 1950.

Kharasch et a1: Grignard Reactions of Nonmetallic Substances, Prentice-Hall, New York, pp. 24 and 49 (1954). 

1. A PAROCES FOR THE PRODUCTION OF A GLYCOL ETHER OF THE GENERAL FORMULA 